In the traditional theories of Chinese Philosophy, there is a great variety in the usage about the metaphor of the mirror /heart-mirroring, each of which was distinguished by its own merits. The author holds the idea that the metaphor of mirror in the theory of moral knowledge embodies that Xin-ti retains the dual nature of both making a clear distinction between rightness and wrongness, and being no diction between right and wrong while one makes a moral judgement. It follows from that, this paper tries to clarify the usage of the metaphor of mirror in the philosophy of Wang Yang-ming, and with extra focus on the theory of one of his most important student, Wang Long-xi. Meanwhile, this paper will also highlight the theoretical characteristic of Long-xi’s idea of moral knowledge – the nature of Knowing the distinction between rightness and wrongness, but transcending the distinction and do not hold on to it. Secondly, the theory of Metaphor of the mirror in moral knowledge concerns the matter of moral judgement and moral practice. Thereby, this paper furthers on the theoretical analysis and comparison between transcending the distinction between right and wrong, which was embodied in Metaphor of mirror in the theory of moral knowledge and Zhuangzi. In addition, this paper will analyze and compare the theory of situational ethics, which takes its center on situation instead of morality; and also the ethics of difference, which is an ethics between moral generalism and moral particularism; thus clarifying the way how to take the heart as the mirror and how taking-the-heart-as-the-mirror makes the judgement between rightness and wrongness; also clarifying the role situation factors and patients play in the moral judgement on the basis of theory of moral knowledge. Making the judgement between rightness and wrongness is of vital significance in our daily life, the failure of which, on the one hand, will result in the chaos of the world with each group has its own standard and judgement about what is right and what is wrong; on the other hand, will end up in a dangerous situation in which one has no idea about how to make a judgement when confronted with moral situation, thus he might lose the ability to make the right judgement and follow the herd. Therefore, Long-xi’s theory of moral knowledge can be of great help to people to make a clear judgement and have a greater certainty when facing moral situation by the way of taking the heart as the mirror.
